Questions tagged [orbital-elements]

Orbital elements are a set of parameters that uniquely identify a specific orbit.

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How can I find the x, y position of apogee and perigee, if I only have the value of distance vector (position) and velocity vector?

I am currently working on a 2D space simulator where I have two bodies; one is still and other is an orbiting object, which I can also control like a rocket. I'm using the Newton's gravity: $F = \...
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Does the James Webb Telescope have a Two Line Element set?

How do you track the position of the James Webb telescope? Does it have its own TLE, or...?
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calculating satellite position and velocity from TLE

I'm trying to calculate satellite orbit from the TLE set at first, I used several libraries including SGP4, Skyfiled to get the initial position and velocity of the satellite at the epoch time I know ...
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When calculating the six Keplerian Orbital Parameters, why do we need both Eccentricity AND the Semi-Major Axis? Doesn't one tell you the other?

Perhaps I am misunderstanding elementary math, but.... How is it possible to know the eccentricity of an ellipse (e) but not the semimajor axis (a)?
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Why does the eccentricity vector always point towards the periapsis of an orbit?

I hope you know that eccentricity can be derived from the position and velocity vectors of a spacecraft (only applies to a two body problem) through this formula : $$\textbf{e} = \frac{\dot{\textbf{r}}...
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Required Orbital Components to Fully Define Orbit

As a follow-up to this question. I have this JSON coming back from the ESA's DISCOSweb API: ...
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Orbital Component Abbreviations

I'm currently in the process of writing an SDK for the ESA's DISCOSweb API. I've come across these attributes on Orbital details. ...
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Trouble understanding the memorandum "Cartesian State Vectors → Keplerian Orbit Elements"

So, I was reading this memorandum to make some c# classes helping with keplerian/newtonian orbital simulations. Then, I found this weird piece for solving for $n$... $n = (0, 0, 1)^T × h = (−h_y, h_x, ...
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Obtaining orbital state vectors given two position vectors and an eccentricity

I was looking into the dynamics of basic 2-system orbits, and I came across a PDF (attached below) showing how to calculate orbital elements given a position and velocity vector. This led me to the ...
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Is there a low Earth orbit with a 24-hour day night cycle?

Are there any possible low-Earth orbits that use precession to match Earth's day/night cycle? So like SSO, but specifically aimed to achieve a 24hr day/night in LEO. If so, what would its parameters ...
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Osculating oscillations! What makes Akatsuki's eccentricity and inclination about Venus vary periodically?

Watching this animated GIF of Akatsuky's orbit I noticed that it seems to "walk" around Venus. Some orbital elements oscillate ~3-4 times a year, others drift and then slowly "step up ...
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Why are there six orbital elements?

I have knew for a long time that there were six orbital elements but I never knew why it was six and not any other arbitrary number? Does it have do with the fact that there is 3 components for both ...
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How to sort orbital positions in the order of following by spacecraft?

I have an orbiting spacecraft which keplerian elements is known. Also, I have a random-ordered list of true anomalies that represents spacecraft's positions on that orbit. How to sort this list to get ...
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How to calculate the Lagrangian points positions?

I have two bodies, one rotates around another on orbit. For i.e. Earth and Sun or Moon and Earth. If we know masses, velocity, distance and keplerian elements of orbit, how can we find the positions ...
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Differences between numerical propagators

I am a trainee who is working on a numeric orbital propagator developed in the company. I can't show you the code but I can tell you that the propagator was developed to work in Simulink. My job was ...
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How to calculate time needed for spacecraft to travel a given number of meters in elliptical orbit or hyperbolic trajectory?

We have elliptical orbit and spacecraft travelling it. I need a formula to calculate a time needed for spacecraft to travel given amount of meters starting from it's current position. Keplerian ...
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Is it possible to detect if orbits intersect or not and positions where they intersect if you know Keplerian elements (2D)?

I have two orbits and I know their Keplerian elements. Is it possible to find positions where two orbits are crossing if those positions exist? Is it possible to do it if spacecrafts are on orbits of ...
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How to calculate future true anomaly for hyperbolic trajectory? Did I make a mistake in my calculations?

I'm trying to calculate future spacecraft's position and velocity at time t. I need to calculate the true anomaly at time t for this. I've already made it for the elliptic orbits and it is working ...
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How to detect the correct sign of the true anomaly for position prediction (clockwise/counterclockwise rotation)?

I calculated spacecraft's keplerian orbital params from position/velocity using this formulas: https://drive.google.com/file/d/11KhEdFboZCPUjfibtjHaDBWtUTNmJxFA/view?usp=sharing Then I can predict ...
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Wrong position during orbit propagation in Unity

I've been working on an orbital physics module for months now, and have reached a barrier. I have two methods, one to convert from Kepler elements to planet-centric coordinates, and the other to ...
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How to find eccentric anomaly by mean anomaly?

Wikipedia gives me the equation M = E - e*sinE I have M and need to find E. How to do it?
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Are 3 points on an orbit enough to determine the shape of it in practice?

In a question about determining orbital elements from two points on an orbit, some discussion arouse regarding how many points are actually necessary, since two is not sufficient. Determining a conic ...
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Find the Orbital Inclination given all other Elements and a Position on the Ellipse

I'm in a situation where I need to determine an orbit's inclination. At my disposal I have all of the orbit's other Keplerian elements, and I have the vector of a single point on the ellipse. Is ...
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How would you calculate a Hohmann transfer going towards the sun?

If you were going from a lower orbit to a higher orbit such as a Earth-Mars transfer, you would use the periapsis of the transfer orbit in the vis-viva equation to calculate the delta V. But if you ...
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Right Ascension of the Ascending Node (RAAN) Drift and Correction

This one can be a very short and easy question, but I wanna know the proper answer of them.. Few days ago I got a questions like: "What kind of perturbation(s) can cause drift on RAAN value of a ...
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How is it possible that the windows on the ISS mostly face Earth only? [duplicate]

In this article astronaut Clayton C. Anderson states that on the ISS the windows "mosty face Earth, which means that it is only possible to see the stars at the very edges of the windows, and ...
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Calculating TLE, or satellite orbit elements based on angle information (RA and Dec) at multiple epochs

new here. I am trying to 'determine' orbital elements of a given satellite. Based on TLE from space-track, or CelesTrak, I observed several satellites resulting in 10 to 20 RA and Dec pairs for each ...
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Obtaining position of GPS and GLONASS satellites from RINEX navigation files

I am currently trying to understand the best way to use the available information in RINEX navigation files for GPS and GLONASS satellites. My main goal currently is to calculate the position at epoch ...
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How would you convert keplerian orbital elments into cartesain vectors with quaternions?

Coverting the keplerian elements to cartesain vectors ( posistion and velocity) is relatievly simple by using rotation matrices show in the document here: https://downloads.rene-schwarz.com/download/...
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what range of orbital inclinations will be needed to reach Mars from the Boca Chica launch site?

When SpaceX fly missions out of Boca Chica in South Texas to Mars what orbital inclination will the launch need to be to put the spacecraft on to best transfer orbit to Mars? And will this vary with ...
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Finding the new true anomaly after performing a maneuver

Given a standard set of orbital elements (angular momentum, semi-major axis, eccentricity, inclination, longitude of the ascending node, argument of periapsis, and true anomaly), and a global time ...
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Rotation matrix / coordinate transformation of maneuver parameters from Prograde, Normal, Radial to Cartesian XYZ?

Say I have a state vector and Keplerian elements of an orbiting spacecraft: Position = [x, y, z] Velocity = [vx, vy, vz] Elements = [a, e, i, $\omega$, $\Omega$, $\nu$] And I have the maneuver I ...
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How can I calculate the future position of a satellite orbiting a central body as a function of time using known orbital elements?

Given the position and velocity vectors at one point in an orbit, one can calculate the keplerian elements and thus graph the subsequent orbital path as a circle/ellipse/parabola/hyperbola depending ...
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Is there a (low-thrust) thrusting strategy to change a single orbital element alone?

In literature, I have found the optimal thrusting directions (in terms of pitch and yaw) for maximizing changes in each orbital element. These optimal changes, while maximizing one element, have an ...
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What's the lowest periapsis of a successful orbit around the Moon? [duplicate]

What's the lowest periapsis of a successful orbit around the Moon ever made by a moon-orbiting spacecraft? Theoretically, Moon-orbiters can go as low as a foot above the surface due to the lack of an ...
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Is Vallado's Revisiting Spacetrack Report #3 still relevant today?

The title pretty much sums it up. I am reading David A. Vallado's Revisiting Spacetrack Report #3, which was published in 2006 and includes source code for the SGP model series. I was wondering, is ...
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How can I edit the STK report output?

I have been dealing for a while on a report which is generated by STK. It contains basically time, azimuth, elevation and range data. Besides those data I need to also generate the theta and phi ...
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How much delta-v does it take to go from one arbitrary orbit to another?

This is, in theory, very basic rocket science. I can't seem to find a solution on here though, so I'm asking in the hopes you'll enlighten me and my amateurish ways. I've got a set of Keplerian ...
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ISS nodal precession

I was confused by JPL Horizons data showing time variations in the ISS longitude of ascending node, until I realized maybe the orbital plane itself rotates around earth... A quick web search then ...
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How to calculate launch window?

Say I want to launch a rocket in the next 5 days for rendezvous with the ISS. I need to figure out when the orbital plane of the ISS will intersect my launch site---e.g., Kennedy. The orbital plane is ...
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Reasonable argument of periapsis?

My intuition for orbital parameters is still poor, so I'm wondering if someone can tell if my argument of periapsis seems reasonable. I'm simulating a launch from Kennedy (28.1 deg latitude, -80.6 deg ...
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Entering elliptical orbit at periapse

Consider a rocket entering an elliptical orbit from launch. Say you want the rocket to enter exactly at periapse---not a few degrees ahead of it, not a few degrees behind it. Can this be done? I have ...
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Setting argument of perigee at orbital insertion?

I've managed to control for altitude, velocity, eccentricity (via flight path angle), orbital inclination, and longitude of ascending node at orbital insertion. Between them, these parameters uniquely ...
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Perigee location?

Suppose I throw a ball eastward from Kennedy and reduce the earth to a point so that the ball can trace an ellipse around it. Because I threw the ball eastward (no vertical or northern velocity ...
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Can we determine the position of an artificial satellite using Kepler's parameters?

I have read that an orbit is defined by Kepler's parameters, so is it possible to determine an exact position of an artificial satellite using those parameters? Forgive me if this is a redundant ...
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Determining the launch period for Hohmann transfer

How do you determine the day of a specific launch? I know there are launch windows but they only refer to the time at which a spacecraft must be launched. For a LEO it is apparently 365 days, but what ...
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Lowest possible lunar orbit and has any spacecraft achieved it?

Because the Moon has no atmosphere a spacecraft can theoretically cruise at a very low orbit. What is the lowest possible lunar orbit and which spacecraft achieved it? Was it the Lunar Module of ...
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How to find/extract the semi-major axis from a TLE with Skyfield?

I have a TLE: 1 33591U 09005A 21024.46740879 .00000049 00000-0 52095-4 0 9997 2 33591 99.1927 41.5349 0014084 172.6670 187.4709 14.12449679616592 And I would like ...
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Computing a new TLE following a delta-v impulse?

Is there some code or a library out there that can take orbital elements, add a known delta-v component and then compute a new TLE? I found this one https://apps.dtic.mil/dtic/tr/fulltext/u2/a289281....
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Launch azimuth from orbital inclination WRT rotating earth?

The formula for launch azimuth given latitude and target orbital inclination goes like this: $$azm = \sin^{-1} \left(\frac{\cos(inc)}{\cos(lat)}\right)$$ I assume the orbital inclination $inc$ and ...